The present invention relates generally to a blind rivet setting tool for setting threaded rivet nuts.
In a blind rivet setting tool of the kind indicated above, the tool is provided with a rotating means which can be actuated by the operator of the tool and which rotates a threaded pin or bolt member forming part of the tool, for screwing the nut on to the threaded pin. The tool also has a forward thrust or advancing means which can be actuated to produce the upsetting operation, by imparting an axial movement to the threaded pin for that purpose. A rotary direction reversing means is provided for rotating the threaded pin in the opposite direction to the direction in which it is screwed into the nut thereon, in order to unscrew the threaded pin from the rivet. In order to perform the sequence of operating procedures set out above, the tool has a first or rearward lever which is operated to rotate the threaded pin in a right-handed direction to cause the threaded pin to engage the nut. When the nut has reached a stop member, the first lever must be released, while the tool may include a slipping clutch as a safety measure in that respect. The tool also has a second lever which is disposed at the base of the tool for effecting the riveting operation, by the spindle being actuated by a compressed air piston, thereby producing an upsetting effect. When that phase in the procedure is concluded, the second lever must be released, and the first lever mentioned above, which is disposed at the rearward end of the tool, must be actuated again in order once again to rotate the threaded pin. In this phase of operation of the tool however, the threaded pin must now be rotated in the opposite direction in order to unscrew it from the threaded nut, so as to release the tool, and that is performed by means of a third actuating means, for example in the form of an additional knob or button. Apart from the design of the tool being of a complicated and expensive nature, operation of such a tool also involves considerable difficulties from the point of view of the operator.
In an endeavour to alleviate such problems, another form of such a tool provides that the operation of screwing the threaded pin into engagement with the nut is effected by applying the tool with pressure, with the rotary movement being automatically switched off when the nut comes into contact with a stop member, wherein, after the actual riveting operation has been performed, by simply pressing a knob or button, the tool is caused to produce a rotary movement in the opposite direction to the first rotary movement. In a further simplified form of the tool, the push button or knob can be omitted and, after the actual riveting operation has been performed, a vent bore is simply closed off to cause the tool to go into a phase of operation in which it produces a rotary movement in the opposite direction to the first rotary movement, thereby to unscrew the tool.
Although operation of that tool is simplified, by virtue of simply closing off a vent opening in order to initiate the unscrewing operation, such closure of the vent opening involves a special actuating action on the part of the operator, which may involve for example taking one hand off the tool in order to close the vent opening, in order thereby to initiate the unscrewing procedure.
However, a blind rivet setting tool is frequently used in situations where it has to carry out a very large number of working operations, so that special or particular actuating actions on the part of the operator, such as the action involved in closing off the vent opening as referred to above, result, in the course of time, in fatigue in the operator, give rise to error, and take up a certain amount of time in operating the tool, so that the total period of time involved in such actuating actions, when considered over a large number of operating procedures, may be of a substantial extent.